New Millennium Experience Company has asked contractors owed money for work on the dome to “back off” after admitting it owes substantial amounts to a number of firms.

A spokesperson for NMEC said: “There is a backlog of smaller-value bills outstanding but we have no figure for the total amount. Our chief executive, Pierre-Yves Gerbeau, has said the situation is unacceptable and we will try to pay these bills as soon as possible.”

A number of contractors also complained that the company’s finance department was difficult to access after it moved from central London to the dome late last year.

Contractors said that following the move letters and phone calls went unanswered. The NMEC spokesperson said: “We moved the finance department into the dome because space was available as contractors moved out. Personnel were unavailable because they were busy clearing invoices.”